Compounded hydrocarbon fuels



3,010,810 COMPOUNDED HYDROCARBON FUELS Robert A. tayner, Albany, and Warren Lowe, Berkeley, Calili, assignors to California Research Corporation, Elan Francisco, Calif., a corporation of Delaware No Drawing. Filed Mar. 22, 1955, Ser. No. 496,076 6 Claims. (Cl. 4462) This invention relates to an improvement in hydrocarbon fuels, and particularly hydrocarbon distillate fuels, to the extent that they are stabilized against deposit formation under varying conditions of static and dynamic flow incident to ultimate introduction into a combustion zone.

The deposit-forming tendencies of hydrocarbon fuels, and particularly the petroleum distillate fuels, are largely dependent upon their composition and the conditions to which they are subjected prior to energy-release through combustion in a combustion zone. Cornpositionwise, the deposit-forming tendencies or instability of the fuel are usually associated with the presence of thermally and/ or catalytically cracked components in the fuel and become increasingly pronounced in the higher boiling range fuels. However, in addition to the effect of the organic components of the fuel, certain conditions of storage, transportation and service prior to combustion also contribute materially to the deposit forming tendencies of the fuel. These conditions are generally conditions of oxidation and result in the formation of soluble and insoluble oxidation products which form the bulk of the deposits laid down on the various metal and other surfaces within the fuel system. Additionally, the presence of nonhydro'oarbon contaminants in the fuel, and particularly metals such as copper and iron, accelerates the oxidative reactions and coincident deposit formation.

The more general oxidative deterioration is obtained as a low temperature oxidation during storage in the presence or" air, and the resulting deposit formation is substantially dependent upon the composition or stability of the fuel. Other types of oxidative conditions which, in addition, promote deposit formation are encountered in the conditions and fuel systems specific to the various types of hydrocarbon fuels. Thus, in the operation of internal combustion engines, whether compression-ignition or spark-ignition, deposit formation is encountered within the induction system and particularly at the intake valves, injector nozzles, and injection plungers. At the areas of deposit formation, the hydrocarbon fuel is subjected to comparatively high temperatures and comes in contact with combustion and exhaust gases containing oxidation precursors, etc. Another illustration of specific deposit formation of hydrocarbon fuels is in the operation of aircraft gas turbine engines wherein the fuel may be employed as a coolant and in heat exchange -with the circulating lubricating oil. In such situations, the fuel is subjected to-skin temperatures of up to 500 F. and results in the deposition of coke-like deposits on the heat exchanger surfaces.

Although certain of these deposit-forming tendencies of the hydrocarbon distillate fuels may be eliminated or minimized by additional refinery processing designed to' extract, alter, and/or remove the oxidation-sensitive and/ nited States Pate 3i ticularly a petroleum hydrocarbon distillate fuel, of a minor amount of a specific class of relatively high molecular weight copolyrner compositions will effect a material reduction in the formation of insoluble sludges, etc., which may be precipitated or carried with the fuel to form deposits within the fuel system and thereby reduce the operating efiiciency of the combustion engine or burner. The class of copolymer compositions which have been determined to be unique in these improving characteristics may be defined as a relatively high molecular weight copolymer which may be obtained by the copolymerization of (A) at least one compound containing an ethylenic linkage and 8 to 30 aliphatic or cycloaliphatic carbon atoms which is copolymerizable through the ethylenic linkage, and (B) at least one compound of the group of il-unsaturated dicarboxylic acids or acid anhydrides, which copolymer is so constituted that the ratio of (A) to (B) is within the range of 1 to 15 and in which 0 to 90 percent of the available carboxyl groups of component (B) are present in the form of their ester, amide, imide, and/or amine salt derivatives.

Within the foregoing definition of the hydrocarbon fuel improving agent, the particular composition chosen for optimum effectiveness is dependent largely upon the particular type of hydrocarbon fuel, its composition, and the environmental conditions to which the fuel is subjected prior to introduction into a combustion zone. Thus, the' specific copolymer composition employed in a motor gasoline for maximum effectiveness in reducing the intake manifold deposits in a spark-ignition, internal combustion engine Will usually differ chemically Within the foregoing classification from the copolymer additives inconporated in a high-boiling burner fuel containing large concentrations of cracked gas oil to eifect the maximum reduction in clogging and plugging of filters, screens, pumps, and the like. In general, the greatest improvement in reduction of deposit-forming characteristics of a hydrocarbon distillate fuel by the incorporation of the subject copolymer addition agent is obtained with 'disconventional burner or furnace oils, particularly for these types of fuel applications, it is desirable to employ an addition agent within the class of relatively high molecular weight copolymers which may be produced through copolymerization of (A) at least one neutral O-polar or unstable components of the .fuel, such practices greatly depreciate the yield of fuel and materially increase the unit fuel costs. However, contrasting the disadvantages V of additional process refining of the distillate fuels, it

has now been discovered that hydrocarbonfuels'may be. I

stabilized against objectionable deposit formation prior to combustion by the incorporation of a unique class of addition agents. I

that the incorporation in a hydrocarbon fuel, and par- 70. According to the presentinvent-ion, it has been found compound containing 8 to 30 aliphaticcarbon atoms and an ethylenic linkage which is copolyrner-izable through said linkage, and (B) 'at. least one compound of the group of mB-unsaturated aliphatic dicarboxylicacids' and their anhydrides to produce a copolymer composition ,in which the components (A) and (-B). are present in the ratio of (A) to (B) withinv the range of l' to 15 and 'in which 0m percent ofthe availablecarboxyl groups of the component (B) are present in the form of their ester, amide, imide, and/or amine salt derivatives.

" his to be understood that the use of the term neutral -O-polar' com-pooh throughout thelspecifieation and claims isdefinitive of such comp'ounds possessing an oxygen cont'aining'polar group, ,such'as ketones, ethers, alde-v 7 hydes, ,carboxylates, etc., and which are neutral in'the boxyl groups.

sense that they do not contain a reactive and replaceable hydrogen or hydroxyl radical as in the case of the free alcohols, carboxylic acids, etc. Again, the use of the term available carboxyl groups is intended to include the dehydrated carboxyl groups present in the acid anhydrides and which are reactive for the purpose of forming the ester, amide, imide, or amine salt derivatives.

These improving agents fundamentally are comprised of at least two copolymen'zable components (A) and (B), which are combined in a specific ratio to form a relatively high molecular weight copolymer possessing certain definite chemical characteristics which are unique in achieving the fuel-improving functions of the additive. The copolymerizable component (A), as previously defined, is primarily employed to impart the required degree of oil solubility to the copolymer composition and is preferably a neutral O-polar compound containing 8 to 30 aliphatic carbon atoms with a copolymerizable ethylenic linkage alpha or beta to the polar group.

In one of its preferred aspects, the copolymerizable component (A) may be defined as a compound having the general formula:

R CI-I =CH(CH -QR where R maybe hydrogen or an acyclic hydrocarbon, Q may be oxygen or a carbonyl-oxy iO or O( i-) radical, R is an acyclic hydrocarbon radical having from 8 to 20 carbon atoms, and x may be 0 or 1. In another of its preferred aspects, and particularly applicable in the preparation of improving agents for higher boiling range hydrocarbon fuels, the component (A) is desirably one or more aliphatic esters containing 8 to 30 carbon atoms and a copolyrnerizable ethylenic linkage alpha or beta to the carboxyl group.

Representative copolymerizable compounds which fall within the scope of the aforementioned definitions of component (A) include the following: olefin hydrocarbons and particularly alkenes such as polyisobutylene and dodecene-l; cycloal'kenes such as cyclohexene, 4-octylcyclo- -hexene-1, and vinylcyclohexane; and styrenes such as poctylstyrene and p-t-butylstyrene; olefinic ethers, representative of which are the vinyl ethers such as vinyl nbutyl ether, vinyl 2-ethylhexyl ether and vinyl p-octylphenyl ether; allyl ethers such as allyl cyclohexyl ether and allyl isobutyl ether; and methallyl ethers such as methallyl n-hexyl ether and meth-allyl octadecyl ether; organic esters in which the copolymerizable ethylenic linkage is contained in the ester radical such as the vinyl, allyl, methallyl and crotyl esters of long-chain aliphatic and cycloaliphatic mono-basic acids, illustrative of which are Vinyl oleate, vinyl palmitate, allyl laurate, allyl stearate, allyl ricinoleate, allyl naphthenate, methallyl caproate, methallyl palmitate, crotyl oleate, crotyl naphthenate, a-methylcrotyl palmitate; organic esters in which the copolymerizable ethylenic linkage is contained in the acid portion of the molecule such as the esters of acrylic, methacrylic, crotonic, maleic, citraconic acids, etc., representative of which are dodecyl acryl'ate, dodecyl methacrylate, cylohexyl methacrylate, decyl vinylacetate, octadecyl isocrotonate, didodecyl maleate, di-Z-ethylhexyl fumarate, phexadecylphenyl-Z-ethylhexyl maleate, didodecyl citraconate, etc.

The other copolymerizable component, identified for convenience as component (B), is employed for the purpose of supplying the requisite active polar constituents in the copolymer composition. As previously indicated, the

fundamental structure of component (B) consists of a dicarboxylic acid or anhydride with a copolymerizable olefinic linkage in the 01$ position to at least one of the can lected from the aliphatic dicarboxylic acids and anhydrides and preferably the cap-unsaturated dicarboxylic acids and More specifically, componentlB) is se-\ in which R and R are either hydrogen or lower alkyl radicals and G is oxygen, in the case of the acid anhydride, or two OH radicals, in the case of the free dicarboxylic acid. 1

Representative of the acids and anhydrides included within the preferred classification of component (B) are maleic acid and its anhydride, itaoonic acid and its anhydride, citraconic acid and its anhydride, fumaric acid, and mesaconic acid, as well as the various substituted derivatives wherein the substituent groups do not interfere with the copolymerizing characteristics of the u,,8-unsaturated or olefinic linkage.

While component (B) has here been defined in terms of a free dicarboxylic acid or anhydride, the final copolymer composition may present up to percent of the available carboxyl groups of component (B) in the form of their ester, amide, imide, and/or amine salt derivatives. These derivatives may be introduced initially into the copolymen'zation reaction by employing as the monomer (B) appropriate mixtures of the dicarboxylic acid derivatives and the free dicarboxylic acid and/ or anhydnide, or the copolymerization may be effected with the dicarboxylic acid or anhydride monomer and the resulting copolymer reacted with the panticular alcohol or amine in appropriate ratio to effect the desired degree of derivative formation.

The desirability of modifying the basic copolymer structure through the use or by the formation of the carboxylic acid derivatives is primarily dependent upon the environmental conditions to which the compounded hydrocarbon fuel is subjected. In addition to the previous variables in hydrocarbon type and projected service conditions, a further selection of optimum copolymer composition is predicated upon the presence or absence of water in the fuel system, e.g., wet or dry fuel system. It has been found that, in general, the modified copolymers in which up to 90 percent of the available carboxyl groups in component (B) are presented in the form of their esterificd or aminated derivatives possess certain performance advantages when employed as an improving agent for hydrocarbon fuels in a wet fuel system. Aside from the improved deposit reduction noted in performance tests in a wet burner fuel system, other collateral improvements, such as corrosion inhibition and improved demulsibility, are attained with proper selection of the copolymer derivatives. The derivatives contemplated within the scope of the invention are such derivatives as may be produced by conventional esterification or amination reactions with the available carboxyl groups of the dicarboxylic acids and/ or anhydrides or component (B). By amination reactions is meant the generalized reactions of ammonia and its substituted derivatives, e.g., primary, secondary and tertiary amines, with a carboxyl group or an acid anhydride group, including the various stages of dehydration, e.g., amine salt, amide, imide, etc. formation. Although these derivatives may be initially presented as an integral function of the monomer (B) to the copolymerization reaction, it is preferred to conduct the copolymerization reaction with thefree dicarboxylic acid and/ or anhydride as the copolymerizable monomer (B) and subsequently modify the resulting copolymer by the csterification or amination reactions to introduce the particular J derivative functions in the desired degree. This preferred mode of preparation facilitates the conduct of the copolymerization reaction; yields a more uniform copolymer backbone; and permits more latitude in the degree of derivative formation.

The type of derivatives which may be formed as contemplated by the invention is necessarily dependent upon the projected conditions of service and improvements desired. Of the various derivatives which may be formed by the esterification and amination reactions, the ester and amide derivatives are preferred. The partial esterification may be conducted with aliphatic, cycloaliphatic, or aromatic monoand polyhydric alcohols, and the partial amination reactions with ammonia or monoand polyamines within a wide range of structural deviation and molecular weight.

For the purpose of illustration, the following representative types of alcohols may be employed in the formation of the ester derivatives. In the monohydric alcohols, the aliphatic alcohols containing usually from 1 to 18 carbon atoms, such as the substituted and unsubstituted alcohols, are preferred although aromatic alcohols, as well as the alicyclic alcohols, such as cyclohexanol, pine oil, abietyl alcohol, etc., may be used. For certain applications, the polyhydric alcohols, such as the glycols, glycerols, pentaerythritols, sorbitans, and polyalkylene glycols and their condensation products, have found merit. In the polyalkylene glycols, the polyethylene and polypropylene glycols, either per se or in combination with varying molecular weights up to about 800, may be employed. Additionally, the ethylene oxide condensation products with fatty amines, fatty acids, and fatty acid amides, may also be used. One generalization in the choice of esterifying alcohol has been noted, namely, that esterification with polyhydric alcohols and amino alcohols, for example glycols, polyalkylene glycols, and alkanolamines, may result in cross-linkage within the polymer structure, as evidenced by gel formation. Accordingly, it is preferred to avoid the presence of free active hydroxyl groups in the ester radical which is accomplished, in the case of the polyethylene glycols, by capping the residual or terminal hydroxyl radical.

On the other hand, representative amines which may be employed to form the aminated derivatives include the monoand poly-functional amines as represented by the primary, secondary, and tertiary aliphatic, aromatic, or alicyclic amines, which preferably contain up to 18 carbon atoms, as well as the polyamines and poly-functional amines, including the amino acids, amino alcohols, amino phenols, polyalkylene polyamines, glyoxalidines or imidazolines and substituted derivatives thereof.

The preparation of the copolymer improving agents involving the copolymerization of the monomers of component (A) and component (B) may be carried out according to the conventional bulk, solution or emulsion methods of polymerization, the choice of which will depend largely upon practical considerations and the particular types of monomers to be copolymerized. .Although considerable variation in ratio of component (A) and component (B) may be indulged, it has been found that the optimum performance characteristics of these copolymer improving agents, which may be represented as A B are obtained when the ratio of component (A) to component (B) lies within the range of from 1 to 15,

and preferably from 1 to 7, or Where m=l to 1512 and mer, such as maleic anhydride, toagreater than 1/1 base fuel stocks of different crude sources.

ratio. However, in the event a ratio, (A) to (B), greater than 1 is desired, this maybe accomplished by employing a mixture of monomers using as the additional monomer (A'), for example, the acrylate esters, methacrylate esters, and/ or diesters of malcic, furnaric, citraconic, etc., acids, to result in a copolymer composition A A 'B where It has been particularly noted in the preferred application of the subject copolymer improving agents in the higher boiling range fuels, such as those boiling predominantly within the range of from 300 to 700 F., and preferably such fuels as contain appreciable concentrations of catalytically cracked gas oil stocks, that a certain optimum relationship between the total number of aliphatic carbon atoms to polar groups within the molecule appears to exist. Evidence has been obtained that for a given concentration the copolymer compositions containing a ratio of aliphatic carbon atoms to polar groups within the range of from 7 to appear to embrace the optimum composition for deposit reduction eifectiveness. In determining this apparent balance between the polar and nonpolar constituents, the aliphatic carbon atoms to be considered are the following:

.and excluding aromatic ring carbon atoms or the carbon atom of the carbonyl groups. As polar groups, the following representative radicals are included: O, OH (either acid, alcohol or phenol),

. -NH -frn, l I and an acid anhydride group as a single unit.

Variations in optimum performance within this range of aliphatic carbon to polar ratio may be obtained with Whereas certain base stocks respond favorably to the copolymers within the entire range of 7 to 90 ratio, other stocks appear more sensitive in that optimum performance is attained with a more restricted range of aliphatic'carbon to polar ratio. However, even the majority of the more sensitive base stocks give an optimum response to the ratios of copolymer compositions in which the aliphatic carbon atoms to polar groups lie within the preferred range of 9 to 40. Alt ough this concept of copolymer compositions appears to correlate generally 'with their erformance in the higher'boiling range fuels, there may be additional composition factors which affect the efficacy of these improving agents in various types of fuel systems and service. However, on the basis of these assumptions, it becomes evident that variations in the aliphatic carbon to polar ratio and hence performance efficacy may be accomplished by the choice of the acid derivative radical and degree of neutralization in the modification or component (B). 7

Upon selection of the desired monomers of compo nents (A) and (B), the copolymerization reaction may be conducted in accordance with the conventional bulk, solution or emulsion methods of polymerization in the presence of a polymerization catalyst or initiator.

of an inert organic solvent, such as benzene, toluene, Xylene orpetroleum naphtha, tofacilitate control of the reaction and handling of the resulting copolymer.

various conventional types of free radical-liberating V initiators or polymerization catalysts may be employed clohexanecarbonitrile or a, t-azodiisobutyronitrile." In

addition, other means for initiating the copolymerization 7 reaction maybe employed, such as the'use of ultraviolet- ,or gamma radiation, as may beobtaine'd fromfir'ra-diation' The copolymen'zation is preferably elfect'edin the presence with a cobalt 60 source. The organic catalyst or initiator may be employed in amounts of 0.1 to percent, and preferably in the range of 0.25 to 2 percent, which amounts may be incorporated in increments as the reaction proceeds. The temperature of copolymerization will vary, depending upon the selected monomeric reactants and solvent employed, and may vary from about 75 to 150 C. The copolymers formed may have a wide range of apparent molecular weight, and usually of the order of at last several thousands.

The majority of the desired copolymer compositions to be employed as improving agents are substantially miscible in hydrocarbon oils, and may be compounded into additive concentrates of at least 10 percent by weight, and preferably up to 70 percent by weight. In the preparation of additive concentrates, the concentration of copolymer in the hydrocarbon vehicle, such as toluene, mixed xylenes, kerosene, or other petroleum fractions, may be limited by the tendency toward gel formation, and in such instances it has been found desirable to incorporate a modifying agent or polar solvent, such as dimethyl formamide, tetrahydrofuran, Z-methyltetrahydrofuran, dioxane, cresylic acids, propylene carbonate, etc., which function as solubilizing agents and cosolvents in the copolymer concentrate. These modifying agents or cosolvents are generally employed in concentrations ranging from 1 to 25 percent of the concentrate. In addition to the copolymer improving agent of this invention, other conventional fuel additives which are compatible with the copolymer improving agent may be incorporated into the concentrate for the purpose of facilitating the handling and blending problems involved in the production of the finished hydrocarbon fuel.

As an illustration of the preparation of representative copolymers of the invention, together with their derivatives, the following examples are presented. It is to be understood, however, that these examples are presented solely for illustration and are not to be construed as limitations of the invention compositions.

EXAMPLE 1 To a glass reaction flask equipped with stirring means, thermometer, reflux condenser and dropping funnel was charged 98 grams (1 mole) of maleic anhydride and 324 grams (1 mole) of allyl stearate along with about 10 cc. of benzene. The contents of the flask were heated to about 225 F. while stirring. About 6.3 grams of benzoyl peroxide dissolved in 100 cc. of benzene was added to the mixture over a period of about 4 hours. The temperature was maintained between about 200 and 230 F. by heating or cooling as necessary during the addition. 4.2 grams of tertiary butyl hydroperoxide was then added, following which the mixture was thoroughly stirred and allowed to stand for 18 hours at 218 F. The mixture thus obtained was distilled to a temperature of 370 F. under a vacuum equal to about 1 mm. of mercury pressure. The product was a glassyappearing copolymer containing equimolar proportions of maleic anhydride and allyl stearate and having an apparent molecular weight of about 90,000 as determined by standard light scattering methods.

EXAMPLE 2 1 mole (253 grams) of lauryl (dodecyl) methacrylate was washed with a 25 percent aqueous solution of sodium carbonate to remove the hydroquinone inhibitor presout. The inhibitor-free lauryl methacrylate was then charged to a three-necked flask equipped for reflux and agitation. 350 ml. of benzene was then added, followed by 1 mole (98 grams) of molten maleic anhydride, and the mixture was agitated and warmed to reflux temperature (l'90'200 F. pot temperature). 0.7 gram of benzoyl peroxide (0.2 weight percent based on monomer charged) dissolved in benzene was added dropwise while heating was continued with agitation at reflux temperature. Refluxing was continued for a total of 6 hours,

after which the reaction product was cooled and poured into a 4-liter funnel containing 2 liters of methanol. After agitation and settling, the copolymer settled as a sticky mass. The methanol was decanted and the precipitated copolymer redissolved in a volume of benzene equivalent to that originally present in the reaction mixture. This solution Was then reprecipitated, and the precipitated copolymer was placed in an evaporating dish under vacuum. The resulting copolymer of lauryl methacrylate and maleic anhydride contained the approximate ratio A B As an alternative to precipitation from methanol, the reaction mixture from the copolymerization was stripped of unreacted maleic anhydride by vacuum distillation. In this procedure, the reaction mixture was diluted with an equal volume of kerosene distillate and warmed under reduced pressure to remove the benzene, maleic anhydride, and the majority of the kerosene carrier. Distillation was continued to a bottoms temperature of 400 F. at 50 mm. mercury pressure (vapor line temperature 350 F.). The distillation bottoms consisted of a solution of copolymer in the higher boiling fractions of kero sene and included small amounts of unreacted lauryl methacrylate.

EXAlVIPLE 3 The copolymerization reaction conducted in accordance with the procedure of Example 2 was repeated employing 1 mole (253 grams) of lauryl methacrylate, 0.255 mole (25 grams) of maleic anhydride, 0.7 gram of benzoyl peroxide, and 275 ml. of benzene. The resulting copolymer of lauryl methacrylate and maleic anhydride contained an approximate ratio of 6/1 or, in other words, A /B EXAMPLE 4 A copolymer concentrate of the lauryl methacrylatemaleic anhydride copolymer prepared in Example 2 (A /B was obtained by diluting the monomer-free copolymer to a 50 percent concentration in an aromatic petroleum distillate. 200 grams of this copolymer concentrate was charged to a reaction flask with 31.5 grams of Adol 63 (saturated tallow alcohols, OH number 214, molecular weight 263) and 0.1 gram of p-toluene sulfonic acid monohydrate in 81 grams of a kerosene distillate solvent. In addition to the reactants, 17 grams of dirnethyl formamide was incorporated as a solubilizing agent. The reaction mix was heated to 200 F. with agitation, and the reaction was maintained under these conditions for 3 hours. The resulting copolymer composition contained approximately 50 percent of the available carboxyl groups of the maleic anhydride or component (B) in the form of their esters with the saturated tallow alcohols.

The foregoing esterification procedure was applied to the copolymer of Example 2 under varying degrees of esterification and employing varying types of alcohol reactants, including lauryl alcohol, isopropanol, capped and uncapped polyethylene glycols of varying molecular weights, abietyl alcohol, ethylene oxide condensation products with fatty acids of varying molecular weights, and ethylene oxide condensation products with fatty acid amides.

EXAMPLE 5 200 grams of the 50 percent concentrate of the copolymer of Example 2, together with grams of an aromatic petroleum solvent and 10.5 grams of dimethyl formamide, were charged to a reaction flask. The copolymer solution was heated to 200 F., and 15.7 grams of di-n-butylamine was added dropwise with stirring over a period of 1 hour. The agitation was continued at 250 F. for an additional 2 hours. The reaction mixture was the cooled and, on analysis by infrared adsorption, it was determined that the resulting composition contained 14.5 percent free available carboxyl groups or, conversely, 85.5 percent of the available carboxyl groups of the original co- EXAMPLE 6 200 grams of an unst-ripped copolymer reaction product, which was taken from an aliquot from a copolymerization reaction conducted as in Example 2, was chargedto a reaction flask with 0.25 gram of benzoyl peroxide. The mixture Was heated to reflux temperature (about 200 F.

bottom temperature), and 11 grams of inhibitor-free styrene was added with vigorous agitation over a period of 1 hour. The reaction mixture was maintained at 200 F. for an additional hour. The product obtained on cooling was a sticky, white, latex-like fluid.

EXAMPLE 7 81 grams of allyl stearate, 49 grams of molten maleic anhydride, and 67 grams of lauryl methacrylate, together with 0.41 gram of benzoyl peroxide and 0.56 gram of t-butyl hydroperoxide, were charged with 10 ml. of benzene to a three-necked flask fitted with reflux and agitating means. The mixture was heated at 2052l0 F. with stirring for 85 hours with no apparent reaction. At this point, 0.97 gram of benzoyl peroxide was added. The temperature rose to 252 F. and thickening was visible. The reaction mixture was immediately cooled to 220 F. and heating continued at this temperature for 3 hours. A further 0.97 gram of benzoyl peroxide in 50 ml. of benzene was added, and heating with agitation'was continued for an additional 3 hours at 220 F. Again, a further increment of benzoyl peroxide (0.97 gram) was added, and heating and stirring at 220 F. was continued for another 8 hours. At the end of this period (total time 100 hours and total catalyst 2 percent byweight), the product was stripped by heating to 426 F. at 0.5 mm. mercury pressure to remove unreacted monomers and solvent. The product obtained was a glassy, brittle polymer, soluble in benzene and petroleum and lubricating oil. The yield obtained was 193 grams, corresponding to a 98 percent yield and containing an equivalent weight of 147 against a theoretical of 155. This ternary copolymer of allyl stearate,"

malleic anhydride and lauryl methacrylate possessed an approximate ratio of l/2/l or A /A /B Numerous representative copolymer compositions falling within the scope of the present invention were subjected to multiple testing procedures designed to determine their eflicacy in reducing deposit-forming character: istics of hydrocarbon fuels under varying conditions of service and application. As has been previously set forth, the deposit-forming characteristics of the higher boiling range fuels, such as the burner oils, furnace oils, and jet fuels, and particularly such fuels as contain appreciable concentrations of cracked gas oils, are probably the most unstable in regard to deposit formation and precipitate sludges, gums, etc., in storage and transit throughout the fuel systems.

To ascertain the merits of the subject improving agents in such unstable fuels, a test procedure was established which has been determined to correlate with actual'service conditions. This test involves the determination of the filter residue or, in other words, the amount of insoluble solids of less than 100mesh particle size, present in distillate fuels as received and the amount of insoluble O p.p.rn. filter residue of compounded fuel) 100 are for 4 weeks at 140 F. In determining the filter residue of fuels as received, the sample is screened through a 100-mesh sieve, and 500 ml. are filtered through a tared Gooch crucible without adding diluent. The crucible is washed with 500 ml. of petroleum ether, dried in an oven at 190 F., cooled in a constant humidity vessel, and weighed. The filter residue is calculated as parts per million.

In determining the filter residue of the fuel on aging in a dry system, an additional 500 ml. sample of the fuel is filtered through filter paper-into an unstopper l-quart bottle and stored at 140 F. for 4 weeks. At the end of this time, the sample is filtered through a tared Gooch crucible. The material adhering to the container is dissolved in 25 ml. of an /20 benzene-alcohol solution. The gums are precipitated by the addition of 500 m1. of petroleum ether, and the mixture is also filtered through the Gooch crucible. The crucible is then washed, dried and weighed as previous.

For the determination in a wet system, the aging pro cedure is identical with the previous except that 10 ml. of distilled water is added to the l-quart bottle before the fuel is aged for 4 weeks at 140 F. At the end of this time, the 5 00 ml. of aged fuel is carefully decanted from the water layer and filtered, then the water layer is filtered through the same crucible, and the bottle is washed and the crucible weighed as before.

While for certain determinations, particularly with varying fuel compositions, the reporting of a filter residue interms of parts per million is desirable, it has been found of advantage when employing standardized base fuels to report additive effectiveness after 4 weeks at 140 F. in terms of percent of stabilization which is determined by the ratio,

p.p.'m. filter residue of base fuel The following filter residue test results were obtained on various base stocks employing an unmodified lauryl methacrylate-maleic anhydride copolymer in the-approximate ratio A /B wherein A designates the lauryl methacrylate component and B the maleic anhydride component. The base stocks were four No. 2 fuels (CS 12-48), identified in the following table, and the test was conducted in a dry system. a

In the following test results, datawere obtained corn 7 paring the aging in a wet and drysystem and illustrating the effect of modification in the "copolymer composition through amination and esterification. The base fuels in this test were a 50/50 blend of a Thennofor -catalytically crackedgas oil and a straight run gas :oil inwhich was incorporated parts 'per million'of the solids which form in distillate fuels during aging at elevat'ed temperatures in either awet or drysystem. The

aging conditions in both the wet and dry determinations.

copolymer improving agent. As in the previous test,

.the representative .copolymer was a lauryl methacrylatemaleic 'anhydride copolymer'. in the approximate ratio.

of 2.7/1. The filter residue ofthe uncompounded base fuel is indicated in parentheses after the filter residue values of the compounded test fuch- In a further series of tests designed to illustrate the degree of effectiveness of the copolymer improving agents of the invention with variations in mole ratio of the A and B components and modification of the copolymer base by esterification and amination reactions with the available carboxyl groups to form partial derivatives thereof, a further series of dry system filter residue tests were conducted. In these tests, the base fuel employed was a. 50/50 blend of a Thermofor catalytically cracked gas oil and a straight run gas oil meeting the U.S. Commercial Standards specifications of a No. 2 fuel oil, and the copolymer improving agents were incorporated in each instance in a concentration of 100 parts per million. The data are reported in terms of percent effectiveness over the uncom-pounded fuel. The base monomers of the copolymer will be identified for the sake of convenience according to the following code: Alaury1 methacrylate; A'-allyl stearate; A -methallyl stearate; and B-maleic anhydride; and the subscript following the respective monomer indicates the approximate mole ratio of the monomer in the copolymer backbone. Except as indicated in the table, the modifying reactants are reacted to form the corresponding derivatives of an estimated 50 percent of the available carboxyl groups in the basic copolymer.

Table III FILTER RESIDUE IN P.P.MZIAFIIIER STORAGE 4 WEEKS AT 1 Percent Additive effectiveness AIS/BI 69 A12] 131-- 77 Ava/B1 75 115/131 94 A4/B 89 As/B 96 Am/B- 95 A'i/Bi 9O Ai/A'i/Ba.-- 96 A2.s/A|/B1 96 ALs/AH/Br 96 A4.5/Bihydroly1ed 100 A4.5/B1-PG 200 n 98 A4-5/B1-PG 400 B (estimated, 20% esterified) 98 A4.i/B1stearyl capped PG 400 (estimated, 15% esterified) 92 Az.1/B1noctadecyl amine 97 A2.7/B1n- 1odecyl alcohol (estimated, 30% esterified) 99 A2-1/B1ab1etyl alcohol (estimated, 36% esterified) 99 Az.1/B1-di-n-butyla 100 A2.1/ 1tertiary octylamine 91 Azalfvzgbranched octadecyl amine (estimated, 21% amina e 100 Az. /B propa"nnl 100 Am/E-p-hydroxy aniline (estimated, 30% aminated) 9G A2.7/B furfury1 amine (estimated, 30% aminated) 98 Az.7/ 1-Duomeen-T b 93 A:.7/BrEt;homid 0/15 (estimated, 20% esterified) s- 98 A2-1/B1-Ethomeen 18/25 6 90 A2.1/BiArmeen 2H-T 9". 98 Az.s/ 1/B1stearyl capped PG 400 96 A2.1/ rstyrene condensation 96 2-1/Bi-a-methyl styrene condensation 100 "KG-polyethylene glycol, of indicated-molecular weight. Com. mercially available through Carbide & Carbon Chemicals Corporation Du0meen-T-fatty diamine of the general formula:

able through the Armour Chemical Division.

Ethomid C/15an N-substitutcd fatty acid amide, the substituents being polyoxyethylene groups. General formula:

The fatty portion is coco amide in this case. x plus 1/ is a total of 5 moles ethylene oxide per mole of Ethomid 0/15. Commercially available through the Armour Chemical Division.

6 Ethomeen l8/25-a tertiary amine having a stearyl alkyl group and two polyoxyethylene groups substituted on the nitrogen of the generalformula:

(CHzCHzOhH R-N CHZCH20)yH Commercially available through the Armour Chemical Division.

B Armeen 2H-T-a mixture of secondary fatty amines with C and C15 alkyl groups and an approximate Mol Combining Wt. of 520. Commercially available through the Armour Chemical Division.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made Without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A combustible hydrocarbon fuel composition comprising a major portion of a hydrocarbon fuel and a minor portion, sufficient to reduce the deposit-forming characteristics of said fuel, of a relatively high molecular Weight copolymer obtained by the copolymerization of (A) monomers selected from the group consisting of aliphatic esters of monocarboxylic acid containing 8 to 30 carbon atoms and a single copolymerizable ethylenic linkage, said ethylenic linkage being alpha and beta to the carboxyl group, and (B) monomers selected from the group consisting of maleic acid and maleic anhydride in which the ratio of (A) to (B) is within the range of 1 to 15 and in which 15 to percent of the available carboxyl groups of (B) are present in the form of monoesters of polyalkylene glycols selected from the group consisting of polyethylene glycols having a molecular weight up to about 800 and monoalkyl ethers of said polyethylene glycols.

2. A concentrate adapted to be incorporated inhydro carbon fuels in concentrations eifective to reduce the deposit-forming characteristics of said fuels consisting essentially of a hydrocarbon'vehicle containing from 10 to 70 percent by weight of a relatively high molecular weight copolymer obtained by copolymerization of (A) monomers selected from the group consisting of aliphatic esters of monocarboxylic acid containing 8 to 30 carbon atoms and a single copolymerizable ethylenic linkage, said ethylenic linkage being alpha and beta to the carboxyl group, and (B) monomers selected from the group consisting of maleic acid and maleic anhydride in which the ratio of (A) to (B) is Within the range of l to 15 and in which 15 to 90 percent of the available carboxyl groups of (B) are present in the form of monoesters of polyalkylene glycols selected from the group consisting of'polyethylene glycols having a molecular weight up to about 800 and monoalkyl ethers of said polyethylene glycols.

3. A combustible hydrocarbon fuel composition comprising a major portion of a hydrocarbon fuel predominantly boiling above 250 F. and a minor portion, sufiicient to reduce the deposit-forming characteristics of said fuel, of a relatively high molecular weight copolymer produced through copolymerization of (A) dodecyl methacrylate and (B) maleic anhydride, in which copolymer the ratio of (A) to (B) is within the range of l to 15 and in which 15 to 90 percent of the available carboxyl groups of (B) are present in the form of monoesters of polyethylene glycol having a molecular weight of about 4. A combustible hydrocarbon fuel composition comprising a major portion of'a hydrocarbon fuel predominantly boiling above 250 F. and a minor portion, sufficient to reduce the deposit forming characteristicsof said fuel, Of a relatively high molecular Weight copolymer produced through copolymerization of (A) dodecyl methacrylate and (B) maleic anhydride, in which copolymer the ratio of (A) to (B) is within the range of 1 to 15 and in which 15 to 90 percent of the available carboxyl groups of (B) are present in the form of rnonoesters of polyethylene glycol having a molecular weight of about 400.

5. A combustible hydrocarbon fuel composition comprising a major portion of a hydrocarbon fuel predominantly boiling above 250 F. and a minor portion, sufiicient to reduce the deposit-forming characteristics of said fuel, of a relatively high molecular Weight copolymer produced through copolymerization of (A) dodecyl methacrylate and (B) maleic anhydride, in which copolymer the ratio of (A) to (B) is about 4.5 to 1 and in which about 50 percent of the available carboxyl groups of (B) are present in the form of monoesters of polyethylene glycol having a molecular weight of about 200.

6. A combustible hydrocarbon fuel composition comprising a major portion of a hydrocarbon fuel predominantly boiling above 250 F. and a minor portion, sufiicient to reduce the deposit-forming characteristics of said fuel, of a relatively high molecular weight oopolymer produced through copolymerization of (A) dodecyl methacrylate and (B) maleic anhydride, in which copolymer the ratio of (A) to (B) is about 4.5 to 1 and in which about 20 percent of the available carboxyl groups of (B) are presen in the form of monoesters of polyethylene glycol having a molecular Weight of about 400.

References Cited in the file of this patent UNITED STATES PATENTS 2,366,517 Gleason Jan. 2, 1945 2,370,943 Dietrich Mar. 6, 1945 2,469,737 McNab et a1 May 10, 1949 2,584,968 Catlin Feb. 12, 1952 2,615,845 Lippincott et al. Oct. 28, 1952 2,666,044 Catlin Jan. 12, 1954 2,728,751 Catlin et al. Dec. 27, 1955 FOREIGN PATENTS 719.648 Great Britain Dec. 8, 1954 

1. A COMBUSTIBLE HYDROCARBON FUEL COMPOSITION COMPRISING A MAJOR PORTION OF A HYDROCARBON FUEL AND A MINOR PORTION, SUFFICIENT TO REDUCE THE DEPOSIT-FORMING CHARACTERISTICS OF FUEL, OF A RELATIVELY HIGH MOLECULAR WEIGHT TERISTICS OF SAID FUEL, OF A RELATIVELY HIGH MOLECULAR WEIGHT COPOLYMER OBTAINED BY THE COPOLYMERIZATION OF (A) MONOMERS SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC ESTERS OF MONOCARBOXYLIC ACID CONTAINING 8 TO 30 CARBON ATOMS AND A SINGLE COPOLYMERIZABLE ETHYLENIC LINKAGE, ATOMS AND SINGLE COPOLYMERIZABLE ETHYLENIC LINKAGE, SAID ETHYLENIC LINKAGE BEING ALPHA AND BETA TO THE CARBOXYL GROUP, AND (B) MONOMERS SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID AND MALEIC ANHYDRIDE IN WHICH THE RATIO OF (A) TO (B) IS WITHIN THE RANGE OF 1 TO 15 AND IN WHICH 15 TO 90 PERCENT OF THE AVAILABLE CARBOXYL GROUPS OF (B) ARE PRESENT IN THE FORM OF MONOESTERS OF POLYALKYLENE GLYCOLS SELECTED FROM THE GROUP CONSISTING OF POLYETHYLENE GLYCOLS HAVING A MOLECULAR WEIGHT UP TO ABOUT 800 AND MONOALKYL ETHERS OF SAID POLYETHYLENE GLYSOLS. GLYCOLS. 